Large parts of Oahu's North Shore, a world-famous surfing spot, are covered in muddy river water after heavy rains washed over Hawaii's already saturated land.
5,500 people have been evacuated north of the state capital, Honolulu, as there is a risk of a 120-year-old dam bursting.
Damage is already estimated at more than $1 billion as buildings and infrastructure have been damaged.
"This will have very serious consequences for us as a state," said Governor Josh Green.
